In message , Paul Corfield
writes

So why don't you simply attempt to board a bus in a zone outside the
validity of your card and see what happens? This is far easier than
divulging the coding and interrogation details of a secure system in a
public forum.

But any travelcard covers buses in any zone. And, next year there will
only be one bus zone anyway....
At an LU station he'd get a 57 which would tell him nothing except the
brand of a well known tinned food manufacturer...
(And a request to pay the difference, of course)
--
Kat Women and cats will do as they please, and men and dogs should relax
and get used to the idea - Robert A. Heinlein